As an engine lubrication technique, there has been popularly employed a technique of lubricating various sliding portions with oil stored in a crankcase (hereinafter referred to as “oil-storage type” engine lubrication technique). With engines employing such an oil-storage type engine lubrication technique (i.e., oil-storage type engines), it is required that an amount or level of stored oil be proper, in order to smoothly lubricate various sliding portions of the engine.
Various oil level detection devices have been known, for example, from Japanese Patent Publication No. SHO-53-44615. The conventional oil level detection device disclosed in the No. SHO-53-44615 publication is provided in a vehicular engine and includes a float switch. When a level of stored oil has decreased or lowered to a preset lower limit level, the device detects the oil level lowering to the lower limit level by the float switch detecting the float having lowered together with the oil level, so that an oil-level warning can be generated by an alarm unit, such as a lamp or buzzer. But, because the disclosed conventional oil level detection device is constructed to only generate an oil-level warning, the engine still remains operative despite the oil level lowering to the lower limit level.
For enhanced durability of the engine, it is conceivable to more positively cope with the oil level lowering, e.g. by positively deactivating the engine upon detection of the oil level lowering to the lower limit level. Namely, arrangements may be made to positively prevent start-up of the engine if the oil is insufficient at the time of the engine start-up. In such a case, however, there arises a need to substantively simplify the overall construction of the oil level detection device and apparatus provided with the detection device.